Before there can be a butterfly there must be the fuzzy little worm with many tiny legs known as the caterpillar. The caterpillar crawls its way through its phase of existence ever so slowly gaining sustenance from only what is right in front of its face. In its little brain there is no other life and certainly no awareness that it could ever soar through the heavens.
Then one day, when the time is right, the little worm starts spinning a cocoon around itself. It takes great effort and time to spin the cocoon. Then, still with no idea of the outcome nor understanding of the process, the worm waits in the darkness until the time is right for it to exert the necessary effort to break through the walls of its own making. It is only then that the process becomes clear and the worm is reborn to fly and delight the eye of any passer-by. It is now a butterfly.
Like the caterpillar, we are born into this plane of existence knowing only what it is to be human, taking for granted the limitations. There is no consciousness that within each of us is the pattern for an entirely different, most beautiful, perfect being that is as far removed from being human as the butterfly is from the caterpillar.
Again, like the caterpillar, it is part of the process of being human to know struggle and darkness. It is also a required part of the process to exert the necessary effort to overcome the darkness if the process is to be completed in its most perfect form. The biggest difference between the caterpillar and we humans is that the caterpillar has been given no choice but to complete its pattern. As humans we are given a choice as to how we live on this plane of existence and a choice as to the outcome.